He was pictured vaulting over the "Gherkin" Swiss Re tower to the slogan "Leap for London" in an image that helped the capital secure the 2012 Olympic Games. But reality has proved far less glamorous for Ben Brown, 21, who has been unable to secure the £15,000 he needs to train full time. He has quit gymnastics and is working in a bank.

Along with Daniel Carter, 18, who was on the world-class potential programme with British Gymnastics, Mr Brown has abandoned the sport competitively.

Sporting groups urged the Government yesterday to inject much-needed investment for athletes to give them the best chance in the 2012 Games and inspire future generations of children.

Mr Brown, who took up the sport aged seven and trained at Sutton School of Gymnastics in Surrey, said: "I can't really blame anybody specifically for the fact that I've had to give up, but I believe the Government has a lot to answer for."

There was plenty of money to create a London arena, he said, "but not a penny is being spent on the young British athletes who might bring home a gold medal". Mr Carter added the decision to quit had been difficult. "If they funded me just £2,000 a year, which is quite minimal, I would carry on with it," he said.

UK Sport, which distributes funding, has told the Chancellor that to achieve the highest possible result in 2012 - fourth place in the medals table - an extra £49.4m must be put towards sport annually for the next seven years.

There were mounting calls yesterday for an immediate announcement as to whether or not this money would be forthcoming. Matthew Greenwood, the performance director of British Gymnastics, the sport's governing body, said the delay in a funding decision was of great concern.

"In our junior ranks we have an awful lot of good competitors. We feel very confident within Great Britain that we have the talent." But he warned: "The clock is ticking. Every day that goes by is a day closer to the Games."

With the 2012 qualification cycle for the men's gymnastics team beginning in 2010, Mr Greenwood said: "The more time that goes by, the more difficult the chance to qualify becomes."

Lord Moynihan, the chairman of the British Olympic Association (BOA), said the loss of athletes through a lack of funding was an example of the devastating effect such confusions and delays could have at the sharp end of sport.

"The BOA hopes that an announcement on future funding is made as soon as possible. We cannot afford to waste another day," he said. "We should be giving our athletes the best chance to reach the medal rostrum at the Olympics in 2012. Such success will inspire generations of children to take up sport, and that surely is the most important legacy of London 2012."

The Department for Culture, Media and Sport defended its funding policy for sport, which it said had tripled under the current government.

"UK Sport will invest £98m between now and the end of the Beijing Olympics in 2008," a spokeswoman said. "Gymnastics will have received £11.1m between 1997 and 2009 to support their best athletes. In addition, £40m has been invested since 1994 in the development of the sport."

She added: "We are in discussions with UK Sport and the Treasury about funding up to 2012."